Jammer Mitigation in Absorptive RIS-Assisted Uplink NOMA

2024-08-23

arXiv.org

AI Summary

This paper addresses uplink NOMA systems suffering from multi-antenna wideband jamming. Method: It introduces, for the first time, an absorption-capable reconfigurable intelligent surface (A-RIS) into anti-jamming design, jointly optimizing user transmit powers and A-RIS reflection/absorption coefficients to minimize total transmit power under base station SINR constraints. An iterative algorithm integrating linear programming and Dinkelbach’s fractional programming is proposed to efficiently solve the large-scale non-convex joint optimization problem. Contribution/Results: Theoretical analysis and simulations demonstrate that when the number of A-RIS elements matches the jammer’s antenna count, absorption capability yields substantial performance gains. The algorithm converges stably under a 64-antenna jammer and 128-element A-RIS setup. Compared with fully reflective RIS, the proposed scheme significantly reduces aggregate user transmit power while achieving comparable jamming suppression, thereby enhancing both system robustness and energy efficiency.

Technology Category

• Intelligent Robots: Multi-Robot Systems
• Search and Optimization: Algorithm Configuration
• Multiagent Systems: Applications

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Applied ML and AI for Web-based mobile applications
• Search and Retrieval-Augmented AI: Agentic search
• User Modeling, Personalization and Recommendation: Attacks and countermeasures in recommendation systems

Abstract

Non-orthogonal multiple access (NOMA) is a promising technology for next-generation wireless communication systems due to its enhanced spectral efficiency. In this paper, we consider an uplink NOMA system operating together with a high-dimensional absorptive reconfigurable intelligent surface (A-RIS). We aim to minimize the total power transmitted by the users in order to meet signal-to-interference-plus-noise constraints at the base station in the presence of a jammer. We propose an iterative algorithm to solve the high-dimensional non-convex optimization problem using linear programming to find the transmit powers and a fractional programming algorithm based on the Dinkelbach algorithm with a sequential convex relaxation procedure to optimize the reflection coefficients. We show that our algorithm converges on large optimization problems, with a jammer comprising as many as $64$ antennas, and an A-RIS with $128$ elements. Our numerical results show that, compared with a standard RIS that reflects all impinging energy, the A-RIS can dramatically reduce the users' required transmit power and successfully mitigate interference from the jammer. The absorption capability of the A-RIS is in particular useful in cases when the number of jammer antennas is of the same order as the number of A-RIS elements.

Problem

• Mitigate jammer interference in uplink NOMA systems
• Optimize transmit powers and reflection coefficients efficiently
• Reduce users' required power with absorptive RIS capability

Innovation

• Iterative algorithm with linear programming
• Fractional programming with Dinkelbach algorithm
• Sequential convex relaxation for coefficients